This invention relates to voltage regulators for alternating current, such as powerline voltage stabilizers, which include a transductor comprising a saturable core and having a control or magnetizing winding and a main winding, the main winding being connected to control the output voltage of the regulator.
In known such voltage regulators, the magnetizing current in the control winding is varied continuously in accordance with variation of the output voltage, generally by means of a direct current amplifier. A disadvantage of such known regulators is that due to the large amount of inductance of the control winding, there is a substantial delay between the variation in the output voltage and the correction thereof. Due to this large inductance, the change in current flow in the control winding follows the variation in output voltage after a delay. In many such known voltage regulators, the consequent delay in correction of output voltage, which is known as "reaction time," may be as much as 150 msec. The long reaction time of known voltage regulators causes essential operational difficulties to arise when they are used to graduate deflection devices or galvanometers, or to feed computers or other devices requiring a more stable feed voltage. While it is known that including a resistor in series with the magnetizing circuit will decrease the reaction time to a certain extent, increasing this resistance also requires increasing the voltage and power of the magnetizing circuit. Such an increase in magnetizing power is uneconomical, in fact, if the series resistor is greatly increased, the power of the magnetizing circuit may be greater than the power to be stabilized.